1. Field of the Invention
The present invention relates to systems for the filtration of air and, more particularly, to air filters utilizing photocatalytic oxidation.
2. Description of Related Art
Some air purification systems utilize a photocatalytic oxidation (PCO) process. The PCO process uses ultraviolet light (UV) and airborne water vapor to activate a catalyst, typically titanium dioxide. The activated catalyst generates hydroxyl radicals. The hydroxyl radicals break down contaminants in the air, such as odors, chemicals, and other organic compounds into less harmful substances, such as carbon dioxide and water.
Referring to FIG. 1, a typical and known air purification system 10 includes a pleated media filter 12, a honeycomb filter 14, and two UV lamps 16, 17 each having a reflector 18, 19, respectively. The system 10 comprises a cabin enclosure that maintains the system 10 as a single unit.
Referring to FIG. 2A, the filter 14 of the known system 10 comprises a honeycomb pattern with cells arranged in a matrix formation and contained and supported by a cardboard frame 11. The honeycomb filter 14 comprises regions of cells. In regions T1 and T2, the inner walls of each cell are coated with a catalyst, such as titanium dioxide. In region C, the inner walls of each cell are coated with carbon.
Referring to FIGS. 2B and 2C, each cell Tcell of regions T1 and T2 has a coating 21 that covers substantially the inner walls of each cell. The walls of each cell are faced perpendicular to the direction of light coming from the lamps 16, 17, which is the same direction as the direction y of air flow through the honeycomb filter 14. The regions T1 and T2 cover an area of the honeycomb pattern configured to receive light from lamps 16, 17 within each catalyst coated cell.
Referring to FIG. 1, air flows from a first side s1 to a second side s2 through the system in a direction y. Air first is forced through to flow through the pleated media filter 12. The media filter 12 captures particles and bioaerosols. The air then passes through the honeycomb pattern of the honeycomb filter 14 where airborne water vapor and UV lamp that impacts catalyst-coated surfaces generate the hydroxyls to destroy organic compounds. The reflector is utilized to reflect light away from the media filter 12, which may degrade under prolonged exposure to UV light. Carbon-coated surfaces of the honeycomb filter further absorb the byproduct produced by the catalyst material, when the material gets activated by UV rays.
In the known system of FIGS. 1 and 2A-C, the lamps 16, 17 and reflectors 18, 19 are positioned within the airflow, along the direction y, which blocks air flow causing a drop in air pressure. The thickness t1 of the lamps 16, 17 and reflectors 18, 19 also add to the width of the cabin enclosure necessary to contain the internal parts of the system 10. Accordingly, improved systems and configurations are needed to make the air purification process more efficient and cost effective, among other needs.